Alberto Contador lost a key team-mate in his Tour de France challenge when the Czech rider Roman Kreuziger was sidelined by Tinkoff-Saxo after possible irregularities emerged with his biological passport.

Tinkoff-Saxo said that the International Cycling Union (UCI) ‘is likely to instigate disciplinary proceedings against [Kreuziger] arising from an alleged violation of its anti-doping rules due to abnormalities detected in his biological passport in 2011 and 2012’.

Stood down: Tinkoff-Saxo announced Roman Kreuziger's removal from their Tour de France team

Potential probe: The Czech rider was found to have possible irregularities with his biological passport for 2011/12

The period in question is when Kreuziger, fifth in last year’s Tour, rode for Astana.

Tinkoff-Saxo added that they ‘have decided, in agreement with Roman, that he will not ride in any races, including the Tour de France, until more information becomes available’.

Lieutenant down: Team leader Alberto Contador will be missing a valuable team-mate for Le Tour